<?php
/**
 * JSMin.php - modified PHP implementation of Douglas Crockford's JSMin.
 *
 * <code>
 * $minifiedJs = JSMin::minify($js);
 * </code>
 *
 * This is a modified port of jsmin.c. Improvements:
 *
 * Does not choke on some regexp literals containing quote characters. E.g. /'/
 *
 * Spaces are preserved after some add/sub operators, so they are not mistakenly
 * converted to post-inc/dec. E.g. a + ++b -> a+ ++b
 *
 * Preserves multi-line comments that begin with /*!
 *
 * PHP 5 or higher is required.
 *
 * Permission is hereby granted to use this version of the library under the
 * same terms as jsmin.c, which has the following license:
 *
 * --
 * Copyright (c) 2002 Douglas Crockford  (www.crockford.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * The Software shall be used for Good, not Evil.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * --
 *
 * @package JSMin
 * @author Ryan Grove <ryan@wonko.com> (PHP port)
 * @author Steve Clay <steve@mrclay.org> (modifications + cleanup)
 * @author Andrea Giammarchi <http://www.3site.eu> (spaceBeforeRegExp)
 * @copyright 2002 Douglas Crockford <douglas@crockford.com> (jsmin.c)
 * @copyright 2008 Ryan Grove <ryan@wonko.com> (PHP port)
 * @license http://opensource.org/licenses/mit-license.php MIT License
 * @link http://code.google.com/p/jsmin-php/
 */

class JSMin {
	const ORD_LF = 10;
	const ORD_SPACE = 32;
	const ACTION_KEEP_A = 1;
	const ACTION_DELETE_A = 2;
	const ACTION_DELETE_A_B = 3;

	protected $a = "\n";
	protected $b = '';
	protected $input = '';
	protected $inputIndex = 0;
	protected $inputLength = 0;
	protected $lookAhead = null;
	protected $output = '';
	protected $lastByteOut = '';
	protected $keptComment = '';

	/**
	 * @param string $input
	 */
	public function __construct( $input ) {
		$this->input = $input;
	}

	/**
	 * Minify Javascript.
	 *
	 * @param string $js Javascript to be minified
	 *
	 * @return string
	 */
	public static function minify( $js ) {
		$jsmin = new JSMin( $js );

		return $jsmin->min();
	}

	/**
	 * Perform minification, return result
	 *
	 * @return string
	 */
	public function min() {
		if ( $this->output !== '' ) { // min already run
			return $this->output;
		}

		$mbIntEnc = null;
		if ( function_exists( 'mb_strlen' ) && ( (int) ini_get( 'mbstring.func_overload' ) & 2 ) ) {
			$mbIntEnc = mb_internal_encoding();
			mb_internal_encoding( '8bit' );
		}
		$this->input       = str_replace( "\r\n", "\n", $this->input );
		$this->inputLength = strlen( $this->input );

		$this->action( self::ACTION_DELETE_A_B );

		while ( $this->a !== null ) {
			// determine next command
			$command = self::ACTION_KEEP_A; // default
			if ( $this->a === ' ' ) {
				if ( ( $this->lastByteOut === '+' || $this->lastByteOut === '-' )
				     && ( $this->b === $this->lastByteOut ) ) {
					// Don't delete this space. If we do, the addition/subtraction
					// could be parsed as a post-increment
				} elseif ( ! $this->isAlphaNum( $this->b ) ) {
					$command = self::ACTION_DELETE_A;
				}
			} elseif ( $this->a === "\n" ) {
				if ( $this->b === ' ' ) {
					$command = self::ACTION_DELETE_A_B;

					// in case of mbstring.func_overload & 2, must check for null b,
					// otherwise mb_strpos will give WARNING
				} elseif ( $this->b === null
				           || ( false === strpos( '{[(+-!~', $this->b )
				                && ! $this->isAlphaNum( $this->b ) ) ) {
					$command = self::ACTION_DELETE_A;
				}
			} elseif ( ! $this->isAlphaNum( $this->a ) ) {
				if ( $this->b === ' '
				     || ( $this->b === "\n"
				          && ( false === strpos( '}])+-"\'', $this->a ) ) ) ) {
					$command = self::ACTION_DELETE_A_B;
				}
			}
			$this->action( $command );
		}
		$this->output = trim( $this->output );

		if ( $mbIntEnc !== null ) {
			mb_internal_encoding( $mbIntEnc );
		}

		return $this->output;
	}

	/**
	 * ACTION_KEEP_A = Output A. Copy B to A. Get the next B.
	 * ACTION_DELETE_A = Copy B to A. Get the next B.
	 * ACTION_DELETE_A_B = Get the next B.
	 *
	 * @param int $command
	 *
	 * @throws JSMin_UnterminatedRegExpException|JSMin_UnterminatedStringException
	 */
	protected function action( $command ) {
		// make sure we don't compress "a + ++b" to "a+++b", etc.
		if ( $command === self::ACTION_DELETE_A_B
		     && $this->b === ' '
		     && ( $this->a === '+' || $this->a === '-' ) ) {
			// Note: we're at an addition/substraction operator; the inputIndex
			// will certainly be a valid index
			if ( $this->input[ $this->inputIndex ] === $this->a ) {
				// This is "+ +" or "- -". Don't delete the space.
				$command = self::ACTION_KEEP_A;
			}
		}

		switch ( $command ) {
			case self::ACTION_KEEP_A: // 1
				$this->output .= $this->a;

				if ( $this->keptComment ) {
					$this->output      = rtrim( $this->output, "\n" );
					$this->output      .= $this->keptComment;
					$this->keptComment = '';
				}

				$this->lastByteOut = $this->a;

			// fallthrough intentional
			case self::ACTION_DELETE_A: // 2
				$this->a = $this->b;
				if ( $this->a === "'" || $this->a === '"' ) { // string literal
					$str = $this->a; // in case needed for exception
					for ( ; ; ) {
						$this->output      .= $this->a;
						$this->lastByteOut = $this->a;

						$this->a = $this->get();
						if ( $this->a === $this->b ) { // end quote
							break;
						}
						if ( $this->isEOF( $this->a ) ) {
							$byte = $this->inputIndex - 1;
							throw new JSMin_UnterminatedStringException(
								"JSMin: Unterminated String at byte {$byte}: {$str}" );
						}
						$str .= $this->a;
						if ( $this->a === '\\' ) {
							$this->output      .= $this->a;
							$this->lastByteOut = $this->a;

							$this->a = $this->get();
							$str     .= $this->a;
						}
					}
				}

			// fallthrough intentional
			case self::ACTION_DELETE_A_B: // 3
				$this->b = $this->next();
				if ( $this->b === '/' && $this->isRegexpLiteral() ) {
					$this->output .= $this->a . $this->b;
					$pattern      = '/'; // keep entire pattern in case we need to report it in the exception
					for ( ; ; ) {
						$this->a = $this->get();
						$pattern .= $this->a;
						if ( $this->a === '[' ) {
							for ( ; ; ) {
								$this->output .= $this->a;
								$this->a      = $this->get();
								$pattern      .= $this->a;
								if ( $this->a === ']' ) {
									break;
								}
								if ( $this->a === '\\' ) {
									$this->output .= $this->a;
									$this->a      = $this->get();
									$pattern      .= $this->a;
								}
								if ( $this->isEOF( $this->a ) ) {
									throw new JSMin_UnterminatedRegExpException(
										"JSMin: Unterminated set in RegExp at byte "
										. $this->inputIndex . ": {$pattern}" );
								}
							}
						}

						if ( $this->a === '/' ) { // end pattern
							break; // while (true)
						} elseif ( $this->a === '\\' ) {
							$this->output .= $this->a;
							$this->a      = $this->get();
							$pattern      .= $this->a;
						} elseif ( $this->isEOF( $this->a ) ) {
							$byte = $this->inputIndex - 1;
							throw new JSMin_UnterminatedRegExpException(
								"JSMin: Unterminated RegExp at byte {$byte}: {$pattern}" );
						}
						$this->output      .= $this->a;
						$this->lastByteOut = $this->a;
					}
					$this->b = $this->next();
				}
			// end case ACTION_DELETE_A_B
		}
	}

	/**
	 * Return the next character from stdin. Watch out for lookahead. If the character is a control character,
	 * translate it to a space or linefeed.
	 *
	 * @return string
	 */
	protected function get() {
		$c               = $this->lookAhead;
		$this->lookAhead = null;
		if ( $c === null ) {
			// getc(stdin)
			if ( $this->inputIndex < $this->inputLength ) {
				$c                = $this->input[ $this->inputIndex ];
				$this->inputIndex += 1;
			} else {
				$c = null;
			}
		}
		if ( ord( $c ) >= self::ORD_SPACE || $c === "\n" || $c === null ) {
			return $c;
		}
		if ( $c === "\r" ) {
			return "\n";
		}

		return ' ';
	}

	/**
	 * Does $a indicate end of input?
	 *
	 * @param string $a
	 *
	 * @return bool
	 */
	protected function isEOF( $a ) {
		return ord( $a ) <= self::ORD_LF;
	}

	/**
	 * Get the next character, skipping over comments. Some comments may be preserved.
	 *
	 * @return string
	 */
	protected function next() {
		$get = $this->get();
		if ( $get === '/' ) {
			switch ( $this->peek() ) {
				case '/':
					$this->consumeSingleLineComment();
					$get = "\n";
					break;
				case '*':
					$this->consumeMultipleLineComment();
					$get = ' ';
					break;
			}
		}

		return $get;
	}

	/**
	 * Get next char (without getting it). If is ctrl character, translate to a space or newline.
	 *
	 * @return string
	 */
	protected function peek() {
		$this->lookAhead = $this->get();

		return $this->lookAhead;
	}

	/**
	 * Consume a single line comment from input (possibly retaining it)
	 */
	protected function consumeSingleLineComment() {
		$comment = '';
		while ( true ) {
			$get     = $this->get();
			$comment .= $get;
			if ( ord( $get ) <= self::ORD_LF ) { // end of line reached
				// if IE conditional comment
				if ( preg_match( '/^\\/@(?:cc_on|if|elif|else|end)\\b/', $comment ) ) {
					$this->keptComment .= "/{$comment}";
				}

				return;
			}
		}
	}

	/**
	 * Consume a multiple line comment from input (possibly retaining it)
	 *
	 * @throws JSMin_UnterminatedCommentException
	 */
	protected function consumeMultipleLineComment() {
		$this->get();
		$comment = '';
		for ( ; ; ) {
			$get = $this->get();
			if ( $get === '*' ) {
				if ( $this->peek() === '/' ) { // end of comment reached
					$this->get();
					if ( 0 === strpos( $comment, '!' ) ) {
						// preserved by YUI Compressor
						if ( ! $this->keptComment ) {
							// don't prepend a newline if two comments right after one another
							$this->keptComment = "\n";
						}
						$this->keptComment .= "/*!" . substr( $comment, 1 ) . "*/\n";
					} else if ( preg_match( '/^@(?:cc_on|if|elif|else|end)\\b/', $comment ) ) {
						// IE conditional
						$this->keptComment .= "/*{$comment}*/";
					}

					return;
				}
			} elseif ( $get === null ) {
				throw new JSMin_UnterminatedCommentException(
					"JSMin: Unterminated comment at byte {$this->inputIndex}: /*{$comment}" );
			}
			$comment .= $get;
		}
	}

	/**
	 * @return bool
	 */
	protected function isRegexpLiteral() {
		if ( false !== strpos( "(,=:[!&|?+-~*{;", $this->a ) ) {
			// we obviously aren't dividing
			return true;
		}

		// we have to check for a preceding keyword, and we don't need to pattern
		// match over the whole output.
		$recentOutput = substr( $this->output, - 10 );

		// check if return/typeof directly precede a pattern without a space
		foreach ( array( 'return', 'typeof' ) as $keyword ) {
			if ( $this->a !== substr( $keyword, - 1 ) ) {
				// certainly wasn't keyword
				continue;
			}
			if ( preg_match( "~(^|[\\s\\S])" . substr( $keyword, 0, - 1 ) . "$~", $recentOutput, $m ) ) {
				if ( $m[1] === '' || ! $this->isAlphaNum( $m[1] ) ) {
					return true;
				}
			}
		}

		// check all keywords
		if ( $this->a === ' ' || $this->a === "\n" ) {
			if ( preg_match( '~(^|[\\s\\S])(?:case|else|in|return|typeof)$~', $recentOutput, $m ) ) {
				if ( $m[1] === '' || ! $this->isAlphaNum( $m[1] ) ) {
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * Return true if the character is a letter, digit, underscore, dollar sign, or non-ASCII character.
	 *
	 * @param string $c
	 *
	 * @return bool
	 */
	protected function isAlphaNum( $c ) {
		return ( preg_match( '/^[a-z0-9A-Z_\\$\\\\]$/', $c ) || ord( $c ) > 126 );
	}
}

class JSMin_UnterminatedStringException extends Exception {
}

class JSMin_UnterminatedCommentException extends Exception {
}

class JSMin_UnterminatedRegExpException extends Exception {
}
